Apparatus for an inductor disposed in a band for method of heat dispersion

ABSTRACT

Embodiments of the present disclosure include an apparatus having a band including a high thermally conductive material is disposed at least partially around an inductor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 63/105,567, filed on Oct. 26, 2020, the disclosure ofwhich is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments of the current invention relate generally to an apparatusand method for heat dispersion for an integrated circuit and, moreparticularly, to a power module apparatus comprised of an inductor and aband comprised of a high thermal material.

BACKGROUND

An integrated circuit (IC) is a nanoscale set of electronic circuits onone small, flat piece of semiconductor material. There are many benefitsof a smaller manufacturing and footprint size, such as increasedprocessing speed and lower manufacturing costs. To maximize thesebenefits, there has been a large push for IC miniaturization. Since1970, electronic circuits have shrunk in size from 10 micrometers to acurrent size of 10 nanometers. There are current efforts to make ICseven smaller.

While there are many benefits in decreasing the size, miniaturizationincreases power consumption and requires integrating heat dissipationmethods and components to make a heat path away from the IC. To assistwith the problems of heat dissipation and power management, an inductoris coupled to the IC. The incorporation of an inductor coupled to the ICcreates a power module, which is necessary to protect voltageregulation, battery management, and power conversion efficiency of theIC.

BRIEF DESCRIPTION OF THE DRAWINGS

The described embodiments and the advantages thereof may best beunderstood by reference to the following description taken inconjunction with the accompanying drawings. These drawings in no waylimit any changes in form and detail that may be made to the describedembodiments by one skilled in the art without departing from the spiritand scope of the described embodiments.

FIG. 1A illustrates an inductor structure for two-phase applications.

FIG. 1B depicts the front and back view of the inductor structure fortwo-phase applications in FIG. 1A, in accordance with some embodimentsof the current disclosure.

FIG. 1C depicts the side-view of the inductor structure for two-phaseapplications in FIG. 1A, in accordance to some embodiments of thecurrent disclosure.

FIG. 2A is a perspective view of one embodiment of the present inventionwhere the top magnetic core is an ‘E’ core and the bottom magnetic coreis an ‘I’ core in accordance with some embodiments of the currentdisclosure.

FIG. 2B is a perspective view of one embodiment of the present inventionwhere the top magnetic core comprises of two ‘U’ cores and the bottommagnetic core is an ‘I’ core in accordance with some embodiments of thecurrent disclosure.

FIG. 2C is a perspective view of one embodiment of the present inventionwhere the top magnetic core comprises of two ‘U’ cores and the bottommagnetic core comprises of two ‘I’ cores in accordance with someembodiments of the current disclosure.

FIG. 3A illustrates an example of an inductor structure disposed in aband to distinguish the top surface of the exterior surface of the bandand the width of the band, in accordance with some embodiments of thecurrent disclosure.

FIG. 3B depicts a front and back view of an example of an inductorstructure disposed in a band in FIG. 3A to distinguish the top andbottom surface of the band, and to distinguish the start and end of theband, in accordance with some embodiments of the current disclosure.

FIG. 3C depicts a side view of an example of an inductor structure in aband in FIG. 3A in accordance with some embodiments of the currentdisclosure.

FIG. 4 is a perspective of an example inductor structure with twoindividual bands disposed around each individual inductor, in accordancewith embodiments of the disclosure.

FIG. 5 illustrates an example of a path of dispersion of heat radiatedfrom power loss of an integrated circuit (IC) around the inductorstructure through the band to a heat sink, in accordance withembodiments of the disclosure.

FIG. 6 is a flow diagram of a method to dissipate heat from the ICaround the power module to the heat sink, in accordance with embodimentsof the disclosure.

FIG. 7 is a flow diagram of a method of fabricating the power module, inaccordance with some embodiments of the disclosure.

DETAILED DESCRIPTION

Typically, integrated circuit (IC) layouts stack components side by sideon a substrate, such as a lead frame or multilayer board. This is knownas a two-dimensional (2D) package. A 2D package is ideal for heatdispersion, since the heat generated from the IC has an uninterruptedheat path to either the top or bottom of the package. To make smallerfootprints, however, designers have started to vertically stack thecomponents, known as a three-dimensional (3D) package. When stacking thecomponents vertically, problems may occur. For example, if the inductoris stacked over the IC, then the heat path is interrupted to thedissipate at the top of the package. If the IC is stacked over theinductor, then the interconnects to the IC are harder to reach and morecomplicated to connect.

Aspects of the present disclosure address the above-noted and otherdeficiencies by providing an apparatus and method for power managementand heat dissipation caused by the miniaturization of ICs and thevertical stacking of components. The IC chip may include a televisioninterface adapter (TIA), one or more application specific integratedcircuits (ASICs), a processing device, such as a computer processingunit (CPU), graphic processing unit (GPU), digital signal processor,field programmable gate array (FPGA), metal-oxide-semiconductorfield-effect transistors (MOSFETs), Gallium Nitride (GaN) transistors(both N and P type), or any other types of processing devices orcircuits. In some embodiments, the power module described herein may bean inductor structure with a high thermally conductive band partiallydisposed around the inductor structure, vertically stacked over an IC.In embodiments, the inductor structure may be a two-inductor that canfunction as either two separate non-coupled inductors or as a coupledinductor.

FIG. 1A illustrates an inductor 10 for two-phase applications accordingto example implementations of the present disclosure. The inductor 10may include one or more of each number of components depicted in FIG.1A. The inductor 10 includes a top magnetic core 11 and a bottommagnetic core 12 with two separate openings with a single turn internalconductor 13 passing through each opening as is shown in further detailat FIG. 1B. In some embodiments, the top magnetic core 11 and the bottommagnetic core 12 may be formed of the same material. In embodiments, thetop magnetic core 11 and the bottom magnetic core 12 may be formed ofdifferent materials.

In an embodiment, the conductors 13 forming the single turn of eachindividual inductor of the inductor 10 are extended beyond the bottomexterior surface of the bottom magnetic core 12, best depicted by a sideview of the inductor 10 as is shown in further detail at FIG. 1C. Theextension may be included so that either passive or active componentscan be placed between the inductor 10 and the substrate or a lead frameto which the inductor 10 will be mounted. The part of the internalconductor 13 that extends beyond the bottom exterior surface createsterminals that are used to mount the structure of the inductor 10 to thesubstrate or lead frame.

FIG. 2A shows a perspective view of the front and back view of anembodiment of the inductor 10. In one embodiment, the overall geometricstructure of the inductor is such that it appears as an E-I magneticcore configuration, where the top magnetic core 11 is an E configurationand the bottom magnetic core 12 is an I configuration.

The function of the inductor 10 created by the individual internalconductors 13 placed through each core opening can be altered tofunction as two separate non-coupled inductors with internal conductors13 that can be used for each phase of the two-phase DC-DC converteroutput, or as a single coupled inductor with two internal conductors 13that can function as separate phases of coupled inductor in a DC-DCconverter. The inductor's 10 performance as a pair of uncoupledinductors or as a two-phase coupled inductor is caused by verticallyoriented and horizontally oriented nonmagnetic gaps placed in the centerleg of the composite-magnetic E core.

FIG. 2B is a perspective view of one embodiment of the presentinvention, where a top magnetic core 11 is formed by two side-by-side Umagnetic cores and when viewed externally, provide the appearance of anE core configuration. The bottom magnetic core 12 is one I magneticcore. The center leg of the composite-E core is formed by the twoadjacent U cores. The vertically oriented nonmagnetic gaps between theadjacent exterior surfaces of the adjacent U cores determine the levelof coupling between the two adjacent inductors.

FIG. 2C is a perspective view of one embodiment of the present inventionwhere the top magnetic core 11 is formed by two side-by-side U magneticcores, and the bottom magnetic core 12 is formed by two side-by-side Imagnetic cores. Horizontally oriented nonmagnetic gaps between theinterfaces of the magnetic U cores and the magnetic I cores are used tocontrol the value of inductance and the saturation current capability ofeach inductor section.

In an embodiment, the top magnetic core 11 and the bottom magnetic core12 are fabricated with a magnetic material such as chromium silicon ironoxide, aluminum silicon iron, molybdenum nickel, nickel iron, ormanganese-zinc (MnZn) ferrite. The iron oxide composite magneticmaterial contains the magnetic field of the inductor 10 within themagnetic material, and prevents the magnetic field from propagatingbeyond the inductor 10 boundary. The DC resistivity of the magnetic corematerial is such that a non-insulated internal conductor 13 can be incontact with the top magnetic core 11 and the bottom magnetic core 12without the consequence of different physically separated points of theconductor being electrically shorted through or by the electricalconductivity of the magnetic core. Typically, the values of the seriesinductance and the series resistance will be as if the conductor wasseparated from the magnetic core by insulation.

FIG. 3A illustrates an example of an inductor structure disposed in aband to distinguish the top surface of thermal band 34 and the width 32of the band 30 that is formed of a high thermally conductive material,in accordance with some embodiments of the disclosure. In someembodiments, the band 30 is formed of a high thermally conductivematerial such as, but not limited to, a formable metal such as copper,silver, gold, aluminum, steel, stainless steel, tungsten, or zinc. Insome embodiments, the highly thermally conductive material can be anon-metal, including, but not limited to, aluminum nitride, graphite,silicon carbide, aluminum, tungsten, or graphite. In some embodiments,the high thermally conductive material may have a thermal conductancegreater than the thermal conductivity of the inductor with values atleast 100 watts per meter per kelvin (W/mK), and preferably greater than200 W/mK.

The thermal band 30 of the inductor 10 may be coupled to and in contactwith heat generating components that are positioned below the conductor.For example, the thermal band 30 of the inductor 10 may be in contactwith one or more processors of a semiconductor device. The heatgenerated from the power loss of these heat generating components maythen be transmitted through the contact points from the heat generatingcomponents to the thermal band 30, as will be described in furtherdetail at FIG. 3C below.

In some embodiments, the width 32 of the band 30 can vary around theinductor structure. The minimum width 32 of the band on the bottom,left, right, and top surface of the inductor 10 may be as wide asnecessary to make a proper thermal connection with the devicesunderneath. The maximum width 32 of the band 30 on the bottom surface ofthe inductor 10 may pass a spacing clearance determined by manufacturingtolerances so the maximum width 32 does not affect the conductiveterminals 13. The maximum width 32 for the left, right, and top surfaceof the inductor 10 can be an overhang of surface of the inductor 10, inwhich the purpose is to maximize surface area.

In one embodiment, limiting nonmagnetic gaps in the pseudo-center leg oftop magnetic core 11, the use of a magnetic material with a suitablyhigh value of DC volume resistivity, and the extension of the internalconductor terminals that extend past the bottom surface of the bottommagnetic core 12 allow for the band 30 to be formed about the peripheryof the inductor 10. The limitation of the nonmagnetic gaps to thepseudo-center leg of the composite inductor 10 eliminates thepossibility of fringing losses associated with close physical proximityof a conductor to a nonmagnetic gap. The high volume DC resistivity ofthe magnetic material allows the top magnetic core 11 and bottommagnetic core 12 to be in physical contact with both internal conductor13 turns and the band 30 without the consequence of circulating currentsdue to shorting of different potentials induced along the conductormaterials. Finally, the extension of the terminals of the individualconductors past the bottom exterior surface of the bottom magnetic core12 allows the terminals to be mountable to a substrate while a suitablythick band 30 encompasses the four exterior surfaces (bottom side, rightside, left side and top side) of the inductor 10. The front side andback side of the top magnetic core 11 and the bottom magnetic core 12are reserved for the input and output terminals and are not covered bythe band 30.

In an embodiment, the nonmagnetic gaps may be limited to thepseudo-center leg of the top magnetic core 11. This will allow for theplacement of the band 30 about the exterior surfaces of the inductor 10without bridging any nonmagnetic, vertically oriented magnetic gaps thatare used to control the amount of coupling between the two individualinductors of a two-inductor structure or the horizontally oriented gapsused to control the inductance and saturation current for eachindividual inductor of the inductor 10.

FIG. 3B depicts a front and back view of an example of an inductorstructure disposed in a band in FIG. 3A to distinguish the top surfaceof thermal band 34 and bottom surface of thermal band 36, and todistinguish the start of band 38 and end of band 40, in accordance withsome embodiments of the current disclosure.

FIG. 3C depicts a side view of an example of an inductor structure in aband in FIG. 3A in accordance with some embodiments of the currentdisclosure.

FIG. 4 illustrates the path of dispersion of heat 44 radiated from powerloss of an integrated circuit (IC) around the inductor 10 through theband 30 to a heat sink 42. The copper band about the composite magneticE-I core structure that was enabled by the specific constructionfeatures of the composite magnetic E-I core structure can be used toconduct heat 44 radiated from the power loss of components of the IC.The heat 44 is dissipated through the thermal conductive path formed bythe band 30 to a heat sink 42 mounted to the top surface of the band 30over the composite magnetic E-I core. Components with thermallysignificant power located between the inductor 10 and the devicesubstrate and/or lead frame can be electrically attached to thesubstrate/headframe and thermally attached to the band 30. The heat 44radiated from the power loss of the components under the inductor 10 istypically conducted through multiple layers of insulation andinterconnects between the device's substrate and end application printedIC. This will create an alternate, more thermally conductive andcontinuous path to a heat sink 42 and is a more efficient mechanism todissipate the heat than ground planes located in the printed circuitboard below the device.

FIG. 5 is perspective of an example of a two-inductor 10 with twoindividual bands 30 disposed around each individual inductor. In someembodiments, the inductor structure may include one or more additionalindividual inductors. Each individual inductor can have a respectiveband 30 disposed around it. The purpose of the band 30 is to cover theoutermost exterior left, right, top, and bottom surfaces of the inductor10. As long as the exterior surfaces are covered with the band 30, thenthe heat produced from the IC has a direct conductive thermal path tothe top of the package. In some examples, the top of the package has aheat sink coupled to the top surface of the band 304.

FIG. 6 is a flowchart illustrating of a method 600 to dissipate heatfrom the IC around the inductor 10 with a band 30 disposed around it tothe heat sink. In some embodiments, method 600 may be performed at leastin part by the inductor 10 and the band 30. Method 600 begins at block602, where the heat radiating from power loss of the components on theIC chip under the inductor 10 disposed in the band 30. The band 30 caneither be one band that is disposed around the exterior surfaces of theinductor 10, or the band 30 can be individual bands 30 that are disposedaround each individual inductor in the inductor 10.

At block 604, the heat collected in block 602 is conducted up and aroundthe inductor 10 through the band 30. The inductor 10 is mounted to theIC by the conductive clip terminals. The high thermally conductivematerial of the band is also thermally coupled to the IC below. In someexamples, a thermal interface material 46 may be disposed between the ICand the band 30.

At block 606, the thermally conductive material of the band 30 is usedas a thermal conductor for the bottom surface of the bottom magneticcore 12 and the top surface of the top magnetic core 11 of the inductor10.

At block 608, the high thermally conductive material of the band 30 isplaced directly on the exterior surface of the magnetic material of thetop magnetic core 11 and the bottom magnetic core 12. Due to theelevated terminals, the band 30 can be made suitably thick so that theband can be used as a thermal conductor between bottom side of theinductor 10 and the top side of the inductor 10.

At block 610, in some embodiments, a heat sink 42 is coupled to the topsurface of the band 30. In some embodiments, the heat sink 42 is a metalclip coupled to the top surface of the band. The metal clip may beformed copper and aluminum. In some embodiments, the heat sink mayinclude passive heat sinks, active heat sinks, bonded heat sinks, or anyother type of heat sink.

FIG. 7 is a flow diagram of a method of fabricating the band 30 anddisposing it around the inductor 10. Method 700 begins at block 702,where a band 30 comprised of a high thermally conductive material isprovided. In some embodiments, the band 30 is formed of a high thermallyconductive material such as, but not limited to, copper, silver, gold,aluminum nitride, silicon carbide, aluminum, tungsten, or graphite.

At block 704, the provided band 30 is disposed at least partially aroundthe inductor 10. In some embodiments, the width of the band 30 isuniform when disposed around inductor 10. In some embodiments, the width32 of the band 30 varies such that it is not uniform when disposedaround the inductor 10.

At block 706, the band 30 is disposed around the inductor 10. The startof the band 38 and the end of the band 40 may not touch on the bottomsurface of the bottom magnetic core 12. The part of the exterior surfaceof the bottom magnetic core between the start of the band 38 and the endof the band 40 may be positioned directly over a heat producingcomponent on the IC. In some embodiments, the heat producing componentmay be a field effect transistor (FET).

At block 708, the band 30 is assembled as a sleeve. In some embodiments,the band 30 includes one or more bands 30 for each individual inductorin the inductor 10.

At block 710, the band 30 that is assembled as a sleeve is slid over theinductor 10. In some embodiments, the band 30 includes one or more bands30 that are assembled as a sleeve and slid over each individual inductorof the inductor 10.

At block 712, the band 30 is coupled to the inductor 10. In someembodiments the band is brazed to the inductor 10. In one example, thestart of the band 38 and the end of the band 40 are connected togetherby a filler metal that is melted and flows between the two ends. Thefiller metal may have a lower melting point than the adjoining metal.The absence of the high thermally conductive material between the startof the band 38 and the end of the band 40 on the exterior surface of thebottom magnetic core 12 over the heat producing component does noteliminate the heat path to the top of the package. This is because theconductivity of the brazing metal is lower than the conductivity of theband 30. The heat will still be conducted to the brazing metal but willfollow a path through the band 30 that is formed of a higher thermallyconductive metal.

In some embodiments, the brazing metal may be, but is not limited to,aluminum-silicon, copper, copper-silver, copper-zinc, copper-tin,gold-silver, nickel alloy, silver, or other types of amorphous brazingfoil.

At block 714, the band is bent around the inductor. The manufacturer maybend the band 30 according to manufacturing tolerances andspecifications.

The preceding description sets forth numerous specific details such asexamples of specific systems, components, methods, and so forth, inorder to provide a thorough understanding of several examples in thepresent disclosure. It will be apparent to one skilled in the art,however, that at least some examples of the present disclosure may bepracticed without these specific details. In other instances, well-knowncomponents or methods are not described in detail or are presented insimple block diagram form in order to avoid unnecessarily obscuring thepresent disclosure. Thus, the specific details set forth are merelyexemplary. Particular examples may vary from these exemplary details andstill be contemplated to be within the scope of the present disclosure.

Any reference throughout this specification to “one example” or “anexample” means that a particular feature, structure, or characteristicdescribed in connection with the examples are included in at least oneexample. Therefore, the appearances of the phrase “in one example” or“in an example” in various places throughout this specification are notnecessarily all referring to the same example

Although the operations of the methods herein are shown and described ina particular order, the order of the operations of each method may bealtered so that certain operations may be performed in an inverse orderor so that certain operation may be performed, at least in part,concurrently with other operations. Instructions or sub-operations ofdistinct operations may be performed in an intermittent or alternatingmanner.

The above description of illustrated implementations of the invention,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosed.While specific implementations of, and examples for, the invention aredescribed herein for illustrative purposes, various equivalentmodifications are possible within the scope of the invention, as thoseskilled in the relevant art will recognize. The words “example” or“exemplary” are used herein to mean serving as an example, instance, orillustration. Any aspect or design described herein as “example” or“exemplary” is not necessarily to be construed as preferred oradvantageous over other aspects or designs. Rather, use of the words“example” or “exemplary” is intended to present concepts in a concretefashion. As used in this application, the term “or” is intended to meanan inclusive “or” rather than an exclusive “or”. That is, unlessspecified otherwise, or clear from context, “X includes A or B” isintended to mean any of the natural inclusive permutations. That is, ifX includes A; X includes B; or X includes both A and B, then “X includesA or B” is satisfied under any of the foregoing instances. In addition,the articles “a” and “an” as used in this application and the appendedclaims should generally be construed to mean “one or more” unlessspecified otherwise or clear from context to be directed to a singularform. Furthermore, the terms “first,” “second,” “third,” “fourth,” etc.as used herein are meant as labels to distinguish among differentelements and may not necessarily have an ordinal meaning according totheir numerical designation.

1. An apparatus comprising: a band comprising a high thermallyconductive material disposed at least partially around an inductor,wherein the band has a gap between a start and an end of the bandpositioned over an integrated circuit die.
 2. The apparatus of claim 1,wherein the high thermally conductive material is a formable metalcomprising copper, silver, gold, aluminum, steel, stainless steel,tungsten, or zinc.
 3. The apparatus of claim 1, wherein the highthermally conductive material comprises a non-metal including aluminumnitride, or graphite.
 4. The apparatus of claim 1, wherein the highthermal conductive material has a thermal conductive value greater thanthe thermal conductivity of the inductor.
 5. (canceled)
 6. The apparatusof claim 1, wherein a width of the band varies around the inductor. 7.An apparatus comprising: a band comprising a high thermally conductivematerial disposed at least partially around an inductor, wherein aminimum width of the band is the minimum width to allow a thermalconnection with one or more terminals of an integrated circuit die. 8.The apparatus of claim 7, wherein the integrated circuit die comprisesan integrated circuit in a package or multiple circuits in a package. 9.The apparatus of claim 1, wherein a maximum width of the band is anoverhang of a width of the inductor.
 10. (canceled)
 11. The apparatus ofclaim 1, wherein the band completely surrounds the inductor.
 12. Theapparatus of claim 1, wherein the band makes direct contact with theinductor.
 13. The apparatus of claim 1, wherein the band improvesthermal performance, magnetic shielding performance, electrostaticshielding performance, or improves placement of the inductor as part ofan assembly.
 14. The apparatus of claim 1, wherein the high thermallyconductive material has a thermal conductivity that is greater than 100watts per meter per kelvin (W/mK).
 15. The apparatus of claim 1, whereinthe high thermally conductive material has a thermal conductivity thatis greater than 200 watts per meter per kelvin (W/mK).